**10. Conclusion**

examinations in asymptomatic patients with moderate (50-70-percent) ICA stenosis have revealed correlation between these plaque findings and development of subsequent ipsilateral

**Figure 5.** Identification of intra-plaque haemorrhage using high spatial resolution, multi-contrast MRI image. (*JACC*

One of the strengths of MRI is the availability of multi-contrast weighted protocols. The most common application of carotid MRI remains the acquisition of an angiogram which uses a bright blood sequence using a 3-dimensional time of flight sequence. This attenuates the signal from stationary (plaque) tissues. Black blood sequences eliminate the luminal signal and help to characterise plaque morphology. [105-109] Combining the information, multiple-contrast weightings can be used to identify all plaque components. [105-110] Plaque compositional characteristics can be assessed using automatic classifiers such as morphology enhanced probabilistic plaque segmentation (MEPPS) algorithms with a high degree of accuracy (Figure-6). [111, 112] Administration of gadolinium-DTPA together with T1-weighted sequences in addition to bright blood time of flight sequence can be used to create maximal intensity projection (MIP) images for measurement of the degree of ICA stenosis [105-107] and accurately measure the thickness of plaque cap in relation to the necrotic core volume. [105-107]

ocular and ischaemic neurological events [108] (Figure-5).

94 Carotid Artery Disease - From Bench to Bedside and Beyond

*Cardiovasc Imaging.* 2009; 2:883-96.)

Over the last 20 years the advances in technology have led to the evolution of non-invasive imaging modalities with high spatial resolution. The application of this technology in the assessment of carotid plaque morphology has advanced our understanding of the natural history of atherosclerotic lesions more than the assessment of histological characteristics of atherosclerotic plaques. Consequently for the first time, plaque morphology could be assessed against the two functions that ultimately matter the most: time and occurrence of future embolic ischaemic events.

New and continuing advances in MRI technology such as higher field strength, phased-array coils, and the application of 3-dimensional and contrast enhanced ultrasound will provide even more tools for assessment of carotid plaque morphology. Gradual application of these modalities in clinical practice will help clinicians select patients with significant ICA stenosis who are likely to benefit from carotid intervention prior to occurrence of ischaemic neurolog‐ ical events.

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Carotid Plaque Morphology: Plaque Instability and Correlation with Development of Ischaemic Neurological Events

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